Are you sure the square drive shaft is seated properly in the clutch drum (motor end) and at the gearbox? It's also possible that you have a stripped gearbox. You can check the gearbox--pull it off the shaft and as you turn the head, see if the shaft end is turning--maybe even stick a screwdriver down in the shaft end to offer a little resistance as you turn the head. I'm guessing you just didn't get the shaft seated properly.

Take the assembly off the front of the motor. Looks like a funnel. I think it has four torx screws. Take a flathead screwdriver and attempt to spin the rotating assembly inside the plastic cover by hand. if it will not spin it must be replaced. I had this exact same problem last week. I tried re seating the shaft, did not work. Once i removed the plastic cover i was able to spray the front bearing with lubricant and it became possible to turn, although with increased resistance. The operators manual does not call for any maintainance on this part, so my hope is that it will be covered under warranty. I think the shavings from the clutch get down in that bearing and cause premature failure.

Take the assembly off the front of the motor. Looks like a funnel. I think it has four torx screws. Take a flathead screwdriver and attempt to spin the rotating assembly inside the plastic cover by hand. if it will not spin it must be replaced. I had this exact same problem last week. I tried re seating the shaft, did not work. Once i removed the plastic cover i was able to spray the front bearing with lubricant and it became possible to turn, although with increased resistance. The operators manual does not call for any maintainance on this part, so my hope is that it will be covered under warranty. I think the shavings from the clutch get down in that bearing and cause premature failure.

This is the clutch drum bearing--if it's locked up (or tight) it's probably not going to get any better with use. This bearing is not expensive (maybe less than $10), but it can be a pain to change on most models. If the unit is still under warranty, it probably will be covered. If not, come back at us for more info if needed.

I must not have had the driveshaft seated properly, because everything spun easily when it was disconnected. I pushed the shaft through to the head and made sure it went in (did a test spin on the head and it moved easily), then connected it to the motor (another test spin) and it worked. Started it up and cleaned up a few areas in the yard.